An Egyptian court on Saturday convicted and sentenced 11 alleged supporters of the country's ousted Islamist president to up to 88 years in prison on charges that include violating a protest law and assaulting police.

The case comes amid a sweeping crackdown by Egypt's military-backed government against the Muslim Brotherhood. Authorities have killed hundreds of Islamists and arrested some 16,000 others since the army removed President Mohammed Morsi, a Brotherhood leader, from office last July.

Hundreds of secular-minded activists and protesters rallied in front of the presidential palace Saturday, demanding the interim president abolish a disputed protest law used prosecute activists. (AP)

Five of the 11 people sentenced Saturday by the court in the southern city of Minya were tried in absentia. The charges against all of the defendants were linked to demonstrations in the town of Samallout to protest the violent dispersal by security forces of two weeks-long pro-Morsi sit-ins that killed hundreds and wounded thousands.

The presiding judge Saturday was the same one who issued death sentences against nearly 530 suspected Islamists in mass trial in March. The ruling stunned rights groups, and drew condemnation from abroad.

In Cairo, meanwhile, hundreds of secular-minded activists and protesters rallied in front of the presidential palace Saturday, demanding the interim president abolish a disputed protest law used extensively over the past months to jail and prosecute activists, including leading figures of the 2011 uprising that toppled longtime autocrat Hosni Mubarak.

The law issued in November bans all political gatherings and protests without prior permission from police. Violators are punished by heavy fines or jail time. Rights groups have sharply criticized the law, calling it draconian.

While marching toward the palace Saturday, some of the protesters chanted "Freedom" and "Abolish the law, get them out of prison." Others carried pictures of jailed activists. A few in the crowd tore down posters for the former military chief Abdel-Fattah el-Sissi, who is now the front-runner in next month's presidential elections.

El-Sissi became hugely popular among a large sector of Egyptians after he led Morsi's removal from power. However, harsh measures adopted by the military-backed government since then - including the jailing of several prominent activists - have opened a rift with a small segment of the secular-minded opposition.